docs: def flat_list(*alist):
      """
      Flat a tuple, list, single value or list of list to flat list
      e.g.
      
      >>> flat_list(1,2,3)
      [1, 2, 3]
      >>> flat_list(1)
      [1]
      >>> flat_list([1,2,3])
      [1, 2, 3]
      >>> flat_list([None])
      []
      """
      a = []
      for x in alist:
          if x is None:
              continue
          if isinstance(x, (tuple, list)):
              a.extend([i for i in x if i is not None])
          else:
              a.append(x)
      return a